UK elms – ‘not out of the woods yet’


Colin Tudge, the author of The Secret Life of Trees, is invited by the UK’s Telegraph newspaper to give his reaction to efforts to breed a Dutch elm disease-resistant species.

Library image from Take CoverIt’s an interesting read as he gives his reaction to this battle with nature, so here it is:

Could the English elm, so sadly laid low by Dutch elm disease, make a comeback? Paul King, who breeds trees at Raine in Essex, is on the case. Nearly 25 years ago he acquired cuttings from a few mature trees. He has now multiplied the tissues to produce a whole new generation of young elms that seem to be resistant (and are on sale for £120 apiece). Scientists at the Forestry Commission’s research centre in Surrey welcome his initiative – they are on the case, too – but are cautious. Resistance, they point out, is a tricky business.

The English elm, Ulmus procera, is probably not a “true” native – Britain has only 39 “truly” native trees – and was most likely introduced by Neolithic farmers from south-east Europe, via Spain. But it is an honorary citizen, treasured for its usefulness and its looks, favourite of landscape painters, notably of Constable; a tree of open woodland but just as happy in hedgerows where, if it was left alone, it flourished by the tens of millions. In the West Country it was known as “the Wiltshire weed”.

The first sign of trouble came in 1910 when the fungus Ophiostoma ulmi, a distant and degenerate cousin of the truffle, started killing trees in mainland Europe. It acquired its name, Dutch elm disease, in 1921 because it was first properly researched in Holland. It arrived in Britain by 1927 and looked very nasty. Happily, the disease died down by the Forties, after killing 10 to 40 per cent of our elms. Dr Tom Pearce of the Forestry Commission predicted, in 1960, that such a thing should not happen again – unless, he added, “the fungus completely changes its present trend of behaviour”.

Which it duly did. A new, closely related species of Ophiostoma appeared in North America – Ophiostoma novo-ulmi. It arrived in Britain in 1967 on imported logs, and throughout the Seventies and into the Eighties it killed about 25 million out of about 30 million elms, including most of the particular English species, Ulmus procera.

Dutch elm disease has all the biological attributes needed to be thoroughly nasty. It is one of the many “wilt diseases” of trees, which spread through the vessels of the xylem and block them. The spores are carried passively with wonderful efficiency in the sap, through the whole tree, and spread via the roots of separate trees that are often joined underground. The spores don’t live long once the tree has died and so should die out as their host succumbs – but they have a trump card: they are carried from tree to tree and from forest to forest by flying bark beetles of the genus Scolytus.

There is some innate resistance among the world’s many species of elm. The Ophiostoma fungus probably arose in Asia, so the Asian elms have evolved in its presence – and have developed considerable resistance. Breeding programmes are afoot in Europe to introduce genes from Asian species into European types by various means – and may yet succeed. Meanwhile, as Paul King has found, even within susceptible species, such as Ulmus procera, there will usually be some resistant strains. If they can be bred, perhaps we will have a new resistant strain.

So why the caution? Well, for one thing, it depends what the tree is really resistant to: the fungus or its insect vector? Paul King’s new trees are probably not resistant to the fungus itself, but are simply less palatable to the beetle. Of course, the fungus can’t usually infest the tree without the beetles – but it surely would be better to be specifically equipped with genes that would protect it even if beetles did get in.

The sad tale of Britain’s elms parallels that of the American chestnut, Castanea dentata – with some intriguing contrasts. For the American Indians and for the first immigrant Europeans, the American chestnut was a wonder tree. Its nuts were a food staple – and supported 40 million wild turkeys for good measure – and its trunks provided timber. There were so many that a squirrel could travel from chestnut to chestnut from Maine to Georgia without setting foot on the ground, or so the story went.

But the overconfident forestry “improvers” of the 19th century were still not content. They began to import Asian species with bigger nuts, to crossbreed. Inevitably, the newcomers came with their own diseases. And the American chestnuts, beset by novel pathogens, succumbed. By the end of the Twenties, the American chestnut, once perhaps the commonest North American broadleaf, was all but gone.

Again, through too much zeal, the Americans felled great swathes of chestnuts to create a firewall against the spread of infection. This failed to contain the disease – but it did, so some biologists suggest, remove the myriad genetic variations from among the wild trees, which might have included some that would have conferred resistance.

By leaving our own beleaguered elms to live on in the hedges, and nurturing the few survivors, as Paul King and others have been doing, we may avoid that final fate. (In truth, the American chestnut might not quite be dead. At least, George W Bush planted one outside the White House on Arbor Day in 2005 – but it is a hybrid: 15 per cent of its genes are from resistant Asian species. It is a sad relic, like an exhumed dodo).

Overall, the message is mixed. We could see the heroic efforts of a few growers and scientists as a triumph of human ingenuity over natural adversity – the continuing tale of “man’s conquest of nature”. Or we could see this endeavour as a desperate, last-ditch attempt to ward off the consequences of our own folly. For these are tales of hubris. We thought we could do what we liked in the name of commerce. But actually, life is more complicated than we ever supposed – and in the end, it is beyond our ken. Cause and effect relationships in nature are non-linear, which means it is intrinsically impossible to predict the outcome, beyond saying it won’t be good.

Source: Telegraph newspaper

Date: 09/06/2010

Wales to update its ancient woodlands map


Forestry Commission Wales has announced plans to update the nation’s Ancient Woodland Inventory.

Take Cover library image In a press release, the commission said that these habitats, which date back to at least the 17th Century, “support many species of plants and wildlife that depend on the evolving but continuous environments created by dead and dying wood and broken sunlight”.

It added that the inventory was first produced about 30 years ago, and since then, technology for gathering data had improved dramatically and better sources of information had come to light.

The update, which will be carried out over the next 12 months, will identify former ancient woodlands that have subsequently been planted with conifer trees to satisfy the demand for timber over many decades.

These woodlands are known as Plantations on Ancient Woodland Sites (PAWS).

This information will guide decisions on restoring some of the PAWS to their natural state by removing non-native trees and planting native broadleaf species such as oak, birch, rowan and ash.

“Such work helps to increase the variety of different plant and wildlife species in the woodland by improving habitats and providing food and shelter,” the commission explained.

Wood pastures – ancient and veteran trees found on grazed sites – will also be systematically recorded as part of the update to the inventory.

Despite the ecological value of wood pasture, it has no legal protection, so identification on the inventory may help protect these sites from damage or destruction.

The concept of  “ancient woodland” was developed in the 1970s and 1980s, when studies showed that woodlands that have had a continuous woodland cover for centuries were typically of higher nature conservation value than those that had developed recently.

The baseline date of 1600 AD was adopted because reasonable maps were available from this time (in England, at least).

But the commission admitted that it was an arbitrary date, and there was no clear ecological cut-off.

Michelle van Velzen, forestry and environment policy and programme manager at Forestry Commission Wales, said: “Ancient woodlands are a precious and finite resource that cannot be recreated.

“This update to the Ancient Woodland Inventory will ensure we have the most comprehensive and accurate information on the extent and nature of ancient woodlands in Wales.”

The update to the inventory will be completed in March 2011 and the new information will be supplied to local authorities for their use when developing planning policy that affects woodland.

Source: Forestry Commission Wales press release

Date: 11/06/2010

Oak disease ‘threatens British landscape’


The continuing spread of a deadly disease that affects the UK’s native oak trees is causing concern among tree professionals and conservation groups.

Take Cover library photoThe BBC’s environment reporter Mark Kinver writes that Acute Oak Decline (AOD), caused by a bacterial infection, can kill an infected tree in just a few years.

Some tree experts are comparing AOD to Dutch elm disease, which killed millions of trees throughout the UK during the 1970-80s.

They said extra funds for more research into the disease were urgently needed.

Although AOD has been confirmed in 55 cases, the number of trees displaying symptoms was steadily increasing, delegates at the Royal Forestry Society’s (RFS) annual conference were told.

The disease affects the UK’s two native species of oak – sessile and pedunculate. To date, there have been no confirmed cases in other species of oaks found in Britain, such as Turkey and red oaks.

‘Extensive bleeding’

Information from Forest Research, the scientific department of the UK Forestry Commission, says the new disease affects oaks more than 50 years old.

Symptoms are “extensive stem bleeding” in which dark fluid seeps from small cracks in the bark and runs down the tree trunk.

In early stages of the disease, the health of a tree’s canopy does not appear to be affected, but it may become thinner as the tree succumbs to AOD.

On its website, Forest Research says: “The incidence of AOD in Britain is unquantified at this stage, but estimates put the figure at a few thousand affected trees.

“The condition appears to be most prevalent in the Midlands and investigations to determine the extent of the disorder are under way.”

A spokesman told BBC News: “Forest Research pathologists have isolated a previously unidentified bacterium they believe is highly likely to be playing a key role in the Acute Oak Decline observed in Leicestershire and elsewhere.

“However, the full cause of the condition is thought likely to be complex, involving a number of factors besides the bacterium. A research report is currently awaiting peer review.”

‘Major threat’

Tree organisations are calling for more funding to be made available to allow researchers to better understand the full impact of the disease.

John Jackson, the organiser of the RFS’s conference, said: “Urgent action is not an option – it’s a necessity.”

Hilary Allison, policy director for the Woodland Trust, added: “The impact of the loss of an iconic tree both from our countryside and towns would be catastrophic, and therefore has the capacity to be a major threat to the UK’s oak woods.”

“I have never seen anything like it,” said Peter Goodwin, co-founder of Woodland Heritage.

“Its spread over the last two years has been quite alarming.”

Mr Goodwin told BBC News that very little was known about the virulent bacteria responsible for the disease.

“We’ve never had a bacterium that is capable of doing what this one is doing.”

He suggested that people were possibly the main way in which the disease was spread from tree to tree, but added that “natural vectors” – such as squirrels, birds and insects – could also play a role.

“I think this is the worrying thing, we all want to know what are the vectors that is spreading it. Is it airborne? We just don’t know.”

Forest Research advises people working in affected areas to take appropriate measures to limit the chances of AOD being carried to new sites.

“The most important thing we can do in this and other cases is to research and understand the causes so that we can provide appropriate management advice for tree owners and woodland managers,” the spokesman added.

“It is also important that we remain vigilant against accidentally importing new and damaging pests and diseases from outside Great Britain.”

Source: BBC News website

Date: 28/04/10

UK’s Woodland Trust to plant a million trees


The Woodland Trust is to plant around a million trees on several sites across the UK to protect the “UK’s equivalent of the rainforest”,  reports Horticulture Week.

“The Plant a Tree appeal will help us plant around a million trees at five key sites across the UK, with others to come in the future,” said conservation officer Fran Hitchinson.

“The trees will buffer ancient woodland, protecting these irreplaceable sites — the UK’s equivalent of the rainforest — and thereby increase their ecological resilience.”

The trust’s 350-hectare Heartwood Forest woodland, near St Albans, will protect three ancient woods allowing wildlife to move and thrive, she added.

Low Burnhall in Durham will be bulked out by 80,000 trees to help conserve the ancient trees and create and shelter for wildflower meadows.

While Milton Woods, at the gateway to the Scottish Highlands in Stirling, will see over 180,000 trees planted to create wildlife havens for otters, owls and wading birds.

The Woodland Trust wants people to donate £15 for a tree to be planted and nurtured for 12 years.

Those who give money will be sent updates and pictures.

Source: Horticulture Week

Date: 01/05/2009

Welsh woodlands to fight climate change


Climate change experts from across Europe will be seeing how the Welsh woodlands are already helping to alleviate the effects of climate change, says a press release from the UK Forestry Commission.

Researchers in Wales are putting in place exciting new ways in which the forests can help prevent flooding as well as locking away millions of tons of carbon dioxide.

Leading members of the new FUTUREforest project will be taken on a fact-finding tour of south Wales on 26-27 March, 2009.

The mission is part of the project’s remit to share experiences and new methods of environmental management to prepare the forests of Europe for climate change.

Specialists from the other six partner regions – Auvergne, France (biodiversity); Brandenburg, Germany (knowledge transfer); Bulgaria (soil protection); Catalonia (natural risks); Latvia (timber production); Slovakia (carbon sequestration) will see some of the effects of climate change on Welsh forests – and some of the solutions in and around Abergavenny.

They will see how woody debris dams, new woodland creation and other flood risk management techniques in the uplands can help to prevent the kind of flooding that has caused millions of pounds worth of damage across Wales.

The 30 strong delegation will be staying at The Hill Education & Conference Centre, Abergavenny, and visiting Forestry Commission Wales woodland sites at Mynydd Du, Usk College and the Woodland Trust’s Great Triley Wood.

“We have already begun to discover much about the way the woodlands of Europe can help us to combat climate change,” said Mike Over, Project Manager of the FUTUREforest project in Wales.

“We hope that experts from our partner regions discover that in Wales we have made some really exciting new discoveries that can help them back in their own countries.”

Source: Forestry Commission press release

Date: 19/03/2009

New tree species found in car park


Scientists who discovered a new species of tree standing beside a country road have named it “no parking” after a sign that was nailed to the trunk, according to a report in the Independent newspaper.

A team of botanists found the tree in a north Devon lay-by while working on a project in which 14 new species and hybrids across the British Isles were discovered.

It was known locally as the No Parking Tree and the nickname has stuck as it is listed in Watsonia, the scientific journal of the Botanical Society of the British Isles, as no parking whitebeam.

The tree’s scientific name is Sorbus admonitor, meaning to admonish or tell off, and it grows at Watersmeet, between the villages of Lynton and Lynmouth.

The research project, led by Dr Tim Rich, head of vascular plants at the National Museum Wales, involved academics from the University of Wales, Bristol University, Exeter University, Oxford University and the Royal Botanic Gardens at Kew.

Source: Independent newspaper

Date: 06/03/2009

Old elm ‘may help save other trees’


Experts hope an elm tree that survived the ravages of Dutch elm disease could hold the key to the species survival in the UK, the BBC News website reports.

The elm was discovered in a Worcestershire hedgerow, near Pershore, two years ago.

It had remained unnoticed because it was assumed all elms in the area had been wiped out by the disease.

The condition, which is carried by a bark beetle, has affected more than 20 million elm trees in the UK since 1970.

Now, Pershore College has taken cuttings from the newly discovered tree and has just planted the first of them.

Bob Hares, from the college, which specialises in horticulture, said that growing cuttings from old trees was difficult.

“The idea is usually to take cuttings from the young trees, which root much more readily, and build up from there,” he said.

The team will not know if these cuttings have the resistance of what they call the “mother tree” until they are about 10 to 15 years old, but they are hopeful.

Now the search is on for other elms that have survived and may also be resistant to Dutch elm disease.

The biggest problem for the college’s team is that most of us do not know what an elm looks like.

John Clarke works for Kemerton Conservation Trust, which works to preserve the natural landscape of Herefordshire, Worcestershire and Gloucestershire.

He said it would be mostly people older than 40 who would be able to recognise elms, “especially people who know trees like farmers and naturalists”.

Elms were once known as the “weed of Worcestershire”. The hope is there are more survivor trees out there to rebuild this much missed part of our landscape.

Anyone who sees a mature elmin the area is urged to contact the conservation trust.

Source: BBC News website

Date: 06/03/2009

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